is all zero's in relation to straight up midnight an actual time?

Answer 1

Yes. The time 1 second before 00:00:01 is 00:00:00.

It is also the time 24:00:00 of the previous day. So if you have a list of times all in the same day, it might be convenient to have the last time as 24:00:00.

Answer 2

Yes (and the plural of zero is zeroes - no apostrophe).

Think of it this way: on a 24-hour clock, one second before midnight is 23:59:59 and one second after midnight is 00:00:01. Midnight itself is 00:00:00.